This invention relates to a blast resistant framework for a window, preferably for a casement window.
The casement window referred to in the present description usually comprises a rectangular (sometimes a polygonal, arched or the like) framework consisting of a frame anchored within an opening in a wall and a sash swing ably mounted thereon with locking means preventing unintended opening of the sash.
IL Patent 115840 to Arpal Aluminium Ltd. describes an adjustable casement window suitable for use as a blast resistant framework illustrated in FIGS. 1 to 3 which are indicated as Prior Art. A rectangular framework 2 for a windowpane 4 is mounted within an opening in a wall 6. The framework comprises an outer frame 8 typically made of steel and anchored within a corresponding rectangular aperture formed in the wall 6 by a portion 11 cast within the wall and by other suitable anchors (not shown), as known per se.
A jamb frame 12 is mounted within the outer frame 8 and consists of an upper frame head 14, a lower frame sill 16, a side shutting jamb 18 and a side hinging jamb 20.
The framework 2 further comprises a window sash 22, which consists of a profiled top rail 24, a bottom rail 26, a shutting stile 28 and a hinging stile 30. The window sash 22 is pivotally mounted with respect to the jamb frame 12 by means of hinges 32, secured respectively to the hinging jamb 20 and the hinging stile 30. The jamb frame 12 and the window sash 22 are typically made of a light metal such as aluminum.
The profiles of the vertical sash members 28 and 30 and the profiles of the horizontal sash members 24 and 26 are respectively formed with inwardly directed pairs of reinforcing flanges 34 and 36 designed to receive the end portion of the window pane 4. These profiles are also provided with suitable seals 38 and 40 for preventing egress or ingress of air, noxious gases, dust and water. The window sash 22 is lockable within the jamb frame 12 by means of a rotary handle 42 mounted on the shutting stile 28 and activating a locking mechanism as known per se, the constituent parts of which being generally and collectively designated as 44 in FIG. 3.
Locking mechanisms which are in use in the casement windows usually comprise upright (and sometimes also horizontal) sliding carrier members which are activated by a rotary handle and, in turn, displace a number of associated locking elements to bring them into their locked state. A blast-resistant casement window with such a locking system is described, for example, in IL Patent 103168 to Arpal Aluminium Ltd., and is effective against distortion and/or detachment with blasts corresponding to one atmosphere pressure (1 Bar=14.2 PSI). Experiments have shown that the above-described frameworks may appear to be ineffective against blasts creating pressures higher than those mentioned above. It has been noticed, that the described air-tight frameworks loose their properties due to bending deformations which appear in vertical and horizontal sash members when blast pressure is momentarily applied to the window pane. Such deformations may cause unlocking of some locking elements, consequent weakening of the lock and sometimes result in collapsing of the window pane into the interior of the shelter or room.
It is therefore an object of the present invention to provide a construction of a sash section for holding a window pane, being capable of effectively withstanding blast pressure if incidentally applied to the windowpane. A second object of the invention is a framework for a window comprising the inventive sash sections.
The above object can be achieved by providing a profiled sash section for a window sash holding a window pane and intended for being installed in an outer frame of a blast resistant window, said sash section comprising:
a main member enabling inter-engagement between the profiled sash member and the outer frame;
a window pane holding member for accommodating and securing an end portion of said window pane in said sash profiled member;
a reinforcing member designed to support the end portion of the window pane and to transmit blast pressure, if incidentally applied to the window pane, to the main member;
said sash section being characterized in that it includes damping means for deforming up to a predetermined limit for at least partially absorbing blast pressure energy applied to the window pane.
In other words, the function of the damping means is to protect the basic structure of the profiled sash section and, consequently, of the window sash from being dangerously deformed by the blast pressure impact.
Preferably, the damping means are profiled, i.e. manufactured in one process with the sash section. However, said damping means may be produced separately (for example by molding) and then incorporated in the sash section.
It should be mentioned, that the inventive sash section may either be constituted by one integral profiled body, or be composed of at least two profiled inter-engaged segments.
The profiled sash section can be selected from a non-exhausting list comprising a hinging stile, a shutting stile, a top rail and a bottom rail. When installing the assembled window sash in the outer frame, said profiled sash sections respectively inter-engage and cooperate with a side hinging jamb, a side shutting jamb, a lower frame sill and an upper frame head.
The main member of the profiled sash section may constitute either a bar-like or tubular body; said main member being adapted for accommodating, at least on one of its surfaces, locking elements, hinges and the like.
Usually, said reinforcing member fills a corner formed between said main member and a plane of the window pane. Preferably, the reinforcing member forms a tubular body being substantially rectangular or trapezoidal in its cross-section.
According to one particular embodiment of the profiled sash member, said reinforcing member is an integral part of said main member which form together a tubular body which may have a cross-section in the form of a rectangle or another polygonal shape.
In accordance with one embodiment of the invention, said damping means comprise at least one damping connector provided between at least one of the following three pairs: the reinforcing member and the window pane holding member, the reinforcing member and the main member, the main member and the window pane holding member.
The damping means in general and the damping connector in particular may constitute a metal piece, bendable if excessive pressure is applied to the window pane. Such a damping connector may either form an integral part of the sash member, or be constituted by a damping insert.
Alternatively, the damping means or the damping connector may be shaped as a metal piece weakened at its particular portion and thus exposed for being deformed and/or broken by the blast pressure energy, thereby partially absorbing thereof.
In a particular case, the damping means may constitute at least one weakened element of said reinforcing member or said main member.
In yet a farther embodiment, the damping means may comprise at least one male-female coupling unit in a non-engaged or partially engaged state, wherein elements thereof are connected, for example, to the window pane holding member and the reinforcing member, respectively; the unit being snap-fittingly engage able only when the incidental blast pressure is applied to the window pane.
In accordance with the second aspect of the invention, there is also provided a blast-resistant framework for a window, the framework comprising a window sash assembled from the sash members as defined above; the window sash being adapted for rigidly and air-tightly securing the window pane in the holding members of said sash members.